DIY Happy has this guide on how to make your own mosquito trap using a 2-liter soda bottle.

1. Cut the top of the bottle as shown

2. Put 200ml hot water in the bottle, stir with 50gram brown sugar. Put the sugar water in cold water to cool it down til 40C (temperature)....

3. After cooling down, put the sugar water in the bottle then add the yeast. No need to mix the yeast with the sugar water. When yeast ferments, it creates carbon dioxide.

4. When you cut the bottle, dont throw the top part away because that’d be needed for step 4 - you see they put the top upside down to fit into the bottle....

5. Put black paper around the bottle since mosquitos like dark places and carbon dioxide. This mosquito trap will then start working. Mosquitos fly around the corner, so the best place to place the trap is at some dark corner.

mosquitoes hide in the shade during the day when its hot. They are more active early in the morning and evenings when its cooler. They usually go on "searching" flights in the evening and night for blood sources. That is where dark shade comes into play. To the person with the skeet-r-done product that probably works for the company: It won't work. Use a product with DEET it is the most effective and it won't hurt you. The other products that have "natural" items like citronella in them aren't effective more than 10-15 mins.